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Objective lens drive device and optical pickup

a drive device and optical pickup technology, applied in the direction of optical recording heads, instruments, data recording, etc., can solve the problems of increasing weight, unable to symmetrically arrange the focusing coil and tracking coil, and unable to generate enough magnetic propulsion force at the coil, etc., to achieve enhanced acceleration sensitivity in the focusing direction and shorten the distance

Inactive Publication Date: 2014-06-03
HITACHI MEDIA ELECTORONICS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an optical pickup for high-density optical discs that is thinner and faster than previous versions. It achieves this by reducing the distance between the focusing coil and magnet, resulting in an objective lens drive device with better acceleration sensitivity. This allows for faster and more precise focusing of the laser beam on the disc.

Problems solved by technology

As a result, a sufficient magnetic propulsion force is generated at the coil with difficulties.
However, in the case of mounting two objective lenses, if the two objective lenses are placed in an objective lens holder with the same dimensions as the above-described one, symmetric arrangement of the focusing coil and the tracking coils is made impossible.
Also, an increased number of objective lenses leads to an increases in weight, which in turn causes a reduction in acceleration sensitivity of the objective lens drive device.

Method used

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  • Objective lens drive device and optical pickup
  • Objective lens drive device and optical pickup
  • Objective lens drive device and optical pickup

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0046]FIG. 1 is a top view of an objective lens drive device according to a first embodiment.

[0047]FIG. 2 is a perspective view of the first embodiment.

[0048]FIG. 3 is a perspective view of a movable section and a transparently-shown magnetic circuit.

[0049]FIGS. 4A, 4B are a perspective view and a front view that illustrate a positional relationship between magnets and coils.

[0050]FIG. 5 is a diagram illustrating a distance relationship between a magnet and a focusing coil or a tracking coil.

[0051]FIG. 6 is a graph showing a relationship between acceleration sensitivity or magnetic propulsion in a focusing direction and a gap between a magnet and a focusing coil when the gap is varied.

[0052]A feature of the first embodiment is configuration in which the magnet-facing face of the focusing coil 3 is located within a range corresponding to the thickness of the tracking coil 4a, 4b in the direction of the gap between the tracking coil and the magnet. The first embodiment will be describ...

second embodiment

[0071]A second embodiment according to the present invention is described with reference to FIGS. 7, 8, 9.

[0072]FIG. 7 is a top view of the second embodiment.

[0073]FIG. 8 is a perspective view illustrating a positional relationship between magnets and coils according to the second embodiment.

[0074]FIG. 9 is a diagram of an objective lens drive device mounted on an optical pickup, according to the second embodiment.

[0075]A feature of the second embodiment is that a focusing coil mounted in the objective lens drive device has a portion close to a tracking coil formed in a rectangular shape. The second embodiment will be described below.

[0076]The same reference numerals denote the same component as those in the first embodiment, and the description is omitted.

[0077]In each diagram, the coil shape and the magnet placement, which are characteristic configuration according to the second embodiment, will be described. The tracking coils 4a, 4b are attached, as a pair of coils, in point-sym...

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Abstract

In an optical pickup equipped with a semiconductor laser, electro-optical components such as a lens, and an objective lens drive device, the objective lens drive device includes objective lenses, a holder holding the objective lenses, a focusing coil, and tracking coils. The focusing coil is wound in parallel to the optical surface of the objective lens, and formed in a parallelogram shape having inclined portions provided near the tracking coils. The two tracking coils are placed on diagonal portions of the lens holder.

Description

BACKGROUND OF THE INVENTION[0001](i) Field of the Invention[0002]This invention relates to an optical pickup which records / reproduces data on / from a disc loaded in an optical disc device or the like, and an objective lens drive device including the optical pickup.[0003](ii) Description of the Related Art[0004]A structure of optical disc devices will be described below.[0005]An optical disc device includes a spindle motor for rotating an optical disc, an optical pickup for recording / reproducing information on / from the optical disc, and a sledge mechanism for moving the optical pickup in the radial direction of the optical disc. The optical disc device further includes control circuits individually controlling the sledge mechanism and a controller comprehensively controlling a reproduction signal from the optical disc or a record signal to the optical disc. One of the mechanisms which directly records / reproduces information on / from the optical disc is the optical pickup.[0006]The oper...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G11B7/00
CPCG11B7/0932G11B7/0933G11B7/0935
Inventor SATO, YOSHIHIROSAITO, HIDENAOHATO, JUNMIZUNO, RYUICHIROKIMURA, KATSUHIKOKATO, SEIICHI
Owner HITACHI MEDIA ELECTORONICS CO LTD